isDeletableFile Implementation + Tests

Foundation/FileManager.swift

@@ -744,9 +744,41 @@ open class FileManager : NSObject {
             access($0, X_OK) == 0
         })
     }
-
+
+    /**
+     - parameters:
+        - path: The path to the file we are trying to determine is deletable.
+
+      - returns: `true` if the file is deletable, `false` otherwise.
+     */
     open func isDeletableFile(atPath path: String) -> Bool {
-        NSUnimplemented()
+        // Get the parent directory of supplied path
+        let parent = path._nsObject.deletingLastPathComponent
+
+        return _fileSystemRepresentation(withPath: parent, andPath: path, { parentFsRep, fsRep  in
+            // Check the parent directory is writeable, else return false.
+            guard access(parentFsRep, W_OK) == 0 else {
+                return false
+            }
+
+            // Stat the parent directory, if that fails, return false.
+            guard let parentS = try? _lstatFile(atPath: path, withFileSystemRepresentation: parentFsRep) else {
+                return false
+            }
+
+            // Check if the parent is 'sticky' if it exists.
+            if (parentS.st_mode & S_ISVTX) == S_ISVTX {
+                guard let s = try? _lstatFile(atPath: path, withFileSystemRepresentation: fsRep) else {
+                    return false
+                }
+
+                // If the current user owns the file, return true.
+                return s.st_uid == getuid()
+            }
+
+            // Return true as the best guess.
+            return true
+        })
     }
 
     private func _compareFiles(withFileSystemRepresentation file1Rep: UnsafePointer<Int8>, andFileSystemRepresentation file2Rep: UnsafePointer<Int8>, size: Int64, bufSize: Int) -> Bool {

TestFoundation/TestFileManager.swift

@@ -16,6 +16,10 @@ class TestFileManager : XCTestCase {
             ("test_moveFile", test_moveFile),
             ("test_fileSystemRepresentation", test_fileSystemRepresentation),
             ("test_fileExists", test_fileExists),
+            ("test_isReadableFile", test_isReadableFile),
+            ("test_isWritableFile", test_isWritableFile),
+            ("test_isExecutableFile", test_isExecutableFile),
+            ("test_isDeletableFile", test_isDeletableFile),
             ("test_fileAttributes", test_fileAttributes),
             ("test_fileSystemAttributes", test_fileSystemAttributes),
             ("test_setFileAttributes", test_setFileAttributes),
@@ -202,6 +206,62 @@ class TestFileManager : XCTestCase {
         ignoreError { try fm.removeItem(atPath: tmpDir.path) }
     }
 
+    func test_isReadableFile() {
+        let fm = FileManager.default
+        let path = NSTemporaryDirectory() + "test_fileAttributes\(NSUUID().uuidString)"
+
+        XCTAssertTrue(fm.createFile(atPath: path, contents: Data(), attributes: nil))
+
+        do {
+            let attrs = try fm.attributesOfItem(atPath: path)
+            let permissions = attrs[FileAttributeKey.posixPermissions] as! UInt16
+            let fileIsReadableFile = (permissions & S_IRUSR == S_IRUSR)
+            let fmIsReadableFile = fm.isReadableFile(atPath: path)
+            XCTAssertTrue(fileIsReadableFile == fmIsReadableFile)
+        } catch let e {
+            XCTFail("\(e)")
+        }
+    }
+
+    func test_isWritableFile() {
+        let fm = FileManager.default
+        let path = NSTemporaryDirectory() + "test_fileAttributes\(NSUUID().uuidString)"
+
+        XCTAssertTrue(fm.createFile(atPath: path, contents: Data(), attributes: nil))
+
+        do {
+            let attrs = try fm.attributesOfItem(atPath: path)
+            let permissions = attrs[FileAttributeKey.posixPermissions] as! UInt16
+            let fileIsReadableFile = (permissions & S_IWUSR == S_IWUSR)
+            let fmIsReadableFile = fm.isReadableFile(atPath: path)
+            XCTAssertTrue(fileIsReadableFile == fmIsReadableFile)
+        } catch let e {
+            XCTFail("\(e)")
+        }
+    }
+
+    func test_isExecutableFile() {
+        let fm = FileManager.default
+        let path = NSTemporaryDirectory() + "test_fileAttributes\(NSUUID().uuidString)"
+
+        XCTAssertTrue(fm.createFile(atPath: path, contents: Data(), attributes: nil))
+
+        do {
+            let attrs = try fm.attributesOfItem(atPath: path)
+            let permissions = attrs[FileAttributeKey.posixPermissions] as! UInt16
+            let fileIsReadableFile = (permissions & S_IXUSR == S_IXUSR)
+            let fmIsReadableFile = fm.isReadableFile(atPath: path)
+            XCTAssertTrue(fileIsReadableFile == fmIsReadableFile)
+        } catch let e {
+            XCTFail("\(e)")
+        }
+    }
+
+    func test_isDeletableFile() {
+        // TODO: Implement test
+        // how to test?
+    }
+
     func test_fileAttributes() {
         let fm = FileManager.default
         let path = NSTemporaryDirectory() + "test_fileAttributes\(NSUUID().uuidString)"